In any sort of construction work in which the earth is perturbed by any great amount, such as excavation for building foundations or altering topological grades, the use of silt barrier structures is required in most locations by state or local law. Originally, baled hay was used for this purpose. In recent years, it has become common to use porous plastic silt barrier sheeting erected with wooden fence posts. The fence posts are typically driven into the ground at regular intervals so as to support the sheeting in a vertical position against the pressure of the silt as it flows against one side of the sheeting and builds up or accumulates to increasing heights on the upstream side of the sheeting. The sheeting is porous, thereby allowing moisture to eventually pass through, while retaining the silt on the upstream side.
In any situation where there is paving, the driving of stakes is impossible, and making holes in the pavement to accommodate silt barrier stakes is generally not permitted. In many construction sites, all of the water will flow toward one or more catch basins (also referred to as storm drains and culverts), and the catch basin is typically located within a paved area where silt barrier stakes cannot be used. Typically, the silt barrier sheeting is simply placed horizontally, right over the catch basin, and weighted down with rocks or sand around the periphery. However, this method does not totally seal the catch basin and significant silt may pass under it. Additionally, it is almost impossible to clear away the silt when it is located right over the catch basin. Furthermore, there is a much greater tendency for the silt barrier sheeting to be ruptured when it is laying horizontally, unsupported over the grating of a catch basin. The foregoing problems are further compounded in the case of curbside catch basins which have an open throat extending vertically upward from the street level within the curb itself.